Radiant Nuclear’s Portable Microreactor Goes for Gold with $300-Million Raise

Radiant Nuclear just finished a fundraising round totaling more than $300 million. Investors contributed funds to bring the startup’s compact, movable nuclear reactors one step closer to being something you might use every day, which is precisely what the California-based firm has been striving toward. They’ve got some breathing room now to actually make it happen, as this fresh investment comes just a few months after a previous round that brought in $165 million, helping Radiant reach the half-billion-dollar threshold.

Doug Bernauer created Radiant in 2020 with one clear purpose in mind: to create a nuclear reactor that wasn’t some clunky beast, but rather a normal-sized device that could be transported on the back of a truck and produce clean power where it was most needed. Right now, diesel generators rumble in many rural locations, whereas Radiant’s primary product, Kaleidos, can generate a solid 1 megawatt of electricity (enough to power a small hospital, a remote mining site, or a large portion of a data center).

Kaleidos is about the same size as a shipping container. You get a truck to the area, hook it up, and voila, power is flowing in no time. There’s no need for a big construction crew or years of permits; simply roll it in, switch it on, and go. And once on site, the reactor will run for 5 years without the need for more fuel. Radiant will come and take it away after its 20-year lifespan to be serviced or disposed of responsibly.

Unlike traditional reactors, there is no requirement for water to cool the core; instead, helium gas and a pair of fans are used to remove excess heat even if the power fails. With fans and some air flow, you don’t even need pumps or external water sources. This makes it particularly beneficial in dry, remote areas where traditional reactors struggle. They use TRISO particles as fuel, which are microscopic uranium kernels encased in layers of carbon and ceramic. These help to keep any fission products under control and can survive extremely high temperatures without melting. This technology has proven itself in other systems, and Radiant is banking on it to keep operations secure and out of the picture.

If you need additional power, multiple units can be connected, making it ideal for large customers such as data centers, military sites, disaster zones, and those living off the grid. Equinix has already signed up for 20 units to back up their facilities, and other deals are in the process, including one for delivery to a US military base by 2028.

The testing phase is advancing swiftly, and in a little more than a year, they’ll transport a demo unit to the Idaho National Laboratory for some fueled testing in a specially protected building. Once that is completed, they will be able to move on and begin selling these items for real. Meanwhile, they’ll be breaking ground on an R-50 facility in Oak Ridge, Tennessee, which will produce 50 reactors each year once it’s fully operational.

The demand for reliable, zero-emission power is increasing quicker than you can say “diesel fuel.” Data centers alone are consuming electricity at an alarming rate, and people who live and work in remote areas are sick of hauling diesel fuel for miles – which is where Radiant comes in: they’re pitching Kaleidos as a direct replacement that’s much quieter, cleaner, and less reliant on dodgy supply chains. The Department of Energy has expressed a significant interest in Radiant and has picked them for more testing and faster evaluations, with development on the safety documents moving as smoothly as clockwork.
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